The ICRC has stated that the violence in Syria constitutes an non-international armed conflict. This is significant because it means the organization tasked with guarding and promoting the Geneva Conventions is declaring that at least portions of the Geneva Conventions (especially Common Article 3) applies to the conflict and unlawful attacks on non-combatants could be prosecuted as war crimes.
At Lawfare Blog, University of Texas’ Robert Chesney has a terrific round-up of legal questions this raises, including the “legal geography of war,” whether Assad will draw on precedent set by US targeted killings to argue that some noncombatants are legitimate targets, whether the war is already internationalized, and how far the ICRC’s view on the matter is decisive.
One other thing that should be noted: Reuters’ story on this declaration makes it sound as if heretofore atrocities against civilians were beyond judicial scrutiny, though as Chesney notes the article does point out that human rights law did and continues to apply. But in fact most of the previous violence in Syria would also be judiciable through the concept of “crimes against humanity” under the Rome Statute of the ICC. Of course, since Syria has signed but not ratified the Rome Statute, the court would only have jurisdiction if Assad or a ranking official traveled to the territory of a state party and were extradited the court, or if the Security Council were to act. Since this appears unlikely, any international war crimes court would need to be constituted ad hoc, most likely by a regional organization. Still, governments could also try Assad or his officials under the principle of universal jurisdiction for some crimes, notably torture.